GB711351A - Improvements in or relating to electric interrupter switches - Google Patents

Abstract

711,351. Thermal switches; snap-action switches. MIDGLEY, A. H., and MIDGLEY, A. M. April 21, 1952 [May 21, 1951; Jan. 25, 1952], Nos. 11829/51 and 2074/52. Class 38(5) A thermal "flasher" or switch has a sheet of spring material 9 with a longitudinal slot 9c forming two strips 9a, 9b, the length of the strip 9b being increased in relation to that of the strip 9a. The latter strip is supported between terminal extension members 5, 6 with interposed insulation 8, the member 6 carrying an adjusting screw 12 and the member 5 carrying a fixed contact 5a which co-operates with a contact centrally disposed on the strip 9b. One end of the sheet 9 is bent so as to normally bow the strip 9b towards the fixed contact 5a, but a tensioned wire 13 connected between the member 5 and the other end of the sheet 9 causes the strip 9b to abut the screw 12. When the wire is heated by the current flowing through it, it relaxes it's tension and the strip 9b moves its contact with a snap-action into engagement with the fixed contact. The wire is then short-circuited and cools re-opening the contacts and the cycle is repeated. The sheet 9 may be provided with a tongue 9d, as shown, carrying a further contact which co-operates with a contact carried on a terminal extension member 15, these additional contacts being adapted to control a circuit (e.g. of a warning light) separate from that through the wire 13, contact 5a and strip 9b (e.g. that of a flashing turning signal light on a vehicle). The strip 9a need not be a continuous strip.